The general service provider network infrastructure consists of a huge installed base of SONET. While providing high reliability and availability of services, SONET is inefficient when provisioning data. These inefficiencies are exacerbated as service demand becomes more packet-based.
E-Line point-to-point and E-LAN multipoint services are in demand by businesses in the financial, retail, medical, media and other industries due to their low cost, ease-of-use, scalability and manageability. To maintain high levels of performance and availability, the service provider network will need to monitor end-to-end performance, remotely troubleshoot the network, and efficiently transport Ethernet traffic. It is cost prohibitive to build a completely new network, and an IP-based network lacks the resiliency of a SONET network. The win-win approach is to maintain the SONET attributes of resiliency, performance monitoring and Operations, Administration & Maintenance (OA&M), but process payloads in a packet-based format instead of in a Time Division Multiplexing (TDM) format. Next-generation SONET technologies such as Generic Framing Procedure (GFP), Virtual Concatenation (VCAT) and Link Capacity Adjustment Scheme (LCAS) were developed for Ethernet service provisioning over SONET (EoS). These EoS capabilities insert Ethernet packets into SONET payloads with some bandwidth efficiencies, but still use TDM for aggregation and transport over the ring. EoS lacks the bandwidth efficiencies needed to adjust for data applications, thereby dedicating bandwidth on the entire SONET ring for each circuit.
Resilient Packet Ring (RPR) converges SONET performance and survivability with efficient processing of packet traffic. RPR addresses the inefficiencies of EoS by implementing bandwidth sharing, spatial reuse and statistical multiplexing. The result of using RPR over SONET instead of EoS is the consumption of significantly less bandwidth and fiber for a given application and the elimination of external Ethernet switches for packet aggregation.
For Triple Play applications, data, voice and video will be packet-based. The network edge to access segment will mainly use Gigabit Ethernet (GigE). Initially, the GigE pipe will transport video programming and data for Internet access. Plain Old Telephone Service (POTS) will be transported separately through the network until Voice over IP (VoIP) is deployed. The video component will consist of High Definition (HD) and Standard Definition (SD) streams using a payload of about 20 Mbps per subscriber. Best effort data will be about 5 Mbps. This total payload will yield an 80%/20% video/data mix respectively over the GigE circuit. RPR over SONET offers the class of service and bandwidth efficiency capabilities to effectively process the data, voice and video streams of triple play services.
This paper will show how a service provider can migrate a purely SONET-based network to one offering packet services, while maintaining performance, survivability and efficiently processing packet data. Examples will show the differences in bandwidth, fiber and equipment utilization of SONET versus EoS versus RPR over SONET for carrier-class Ethernet and triple play services.
© 2006 Optical Society of AmericaPDF Article
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